After the promotion of the new potato varieties, with the increase of planting years, the yield decreased year by year, the plants became shorter, the potatoes became smaller, and the stems and leaves were abnormal, such as the leaves and leaves curled or shrunk. This phenomenon is called degradation. The main cause of potato degradation is viral disease, an infectious virus. This disease is spread in the field by insects (mainly aphids) or leaf contact. )
It can lead to the physiological metabolism of plants, reduced vitality, resulting in a large reduction in production. In severe cases, it can reduce production by 70%--80%, and there is no even production of commodities. At present, there are 18 viruses that can infect potato in the world, including one kind of virus and two kinds of mycoplasma. There are 9 species of viruses that are specifically parasitic on potatoes, and 7 species that are found in the country. The seven viruses are Potato Virus (PVX), Potato Virus 4PVY, Potato Virus (PVS), Potato Virus M (PVM), Potato Violet Mosaic Virus (PVMA), Potato Virus A (PVA), and Ma Xing. Leaf Rolling Virus (PLRV). In addition, some viruses that infect tobacco, cucumber, tomato, etc. also infect potatoes.
Symptoms There are 3 types of common potato virus disease. Chlorophyll of mosaic leaves is unevenly distributed, showing greenish greenish greenish or yellowish greenish mottled mosaics. In severe cases, the leaves are shrunken, the whole plant is dwarfed, sometimes accompanied by veins and leaves transparent; necrotic type leaves, veins,
Petiole, shoots and stems may have brown necrotic spots. The development of lesions is connected to necrotic streak. When severe, the whole leaf is withered or wilting. The leaf-wrapped leaves turn inward along the main vein or from the edge and become hard and leathery. In severe cases, each leaflet is tubular. In addition, there was compound infection that caused potato plaque necrosis.
The pathogenic potato virus X (PVX for short) causes light mosaic disease on potatoes, sometimes with mottled or ring spots. The virions are linear, 480 to 580 nm long, and have a wide host range. Systemic infections are mainly of the Solanaceae family. The virus dilution limit was 100,000 to 1,000,000 times, and the inactivation time of the inactivated domain 68-75°C was more than one year in vitro. The potato virus S (Potato virus S, PVS for short) causes mild shrinking and mosaicism or non-obvious disease in potatoes. The virions are linear, 650 nm long, and their host range is narrow. Plants that are infested by the system are limited to a few plants of the Solanaceae family. The disease sap dilution point is 1-10 times, the passivation temperature is 55-60°C, and the survival time in vitro is 3-4 days. Potato virus A (PVA) causes mild mosaic or non-obvious disease in potatoes. The virions are linear, 730 nm long, and their host range is narrow, infecting only a few plants of the Solanaceae family. Disease sap dilution point 10 times, passivation temperature 44-52 °C, 12-18 hours of survival in vitro. Potato virus Y (PVY) causes severe mosaic or necrotic spots and necrotic streak spots on potatoes. The virions are linear and 730 nm long. The virus has a wide host range.
Can infect a variety of plants in Solanaceae. Disease sap dilution point 100 to 1000 times, passivation temperature 52-62 °C, in vitro survival period of 1-2 days. The potato leafroll virus (Potat oea fro 1 1 1 virus, abbreviated as PLrV) has a virosomal globular shape with a diameter of 25 nm. The host area of ​​the virus is mainly Solanaceae. Roll leaf disease was induced on potato, the virus dilution point was 10000 times, the passivation temperature was 70°C, the survival time was 12-24 hours in vitro, and 4 days survived at a low temperature of 2°C. In addition, TMV can also infect potatoes.
Transmission routes and onset conditions In addition to PVX, the above viruses can be transmitted through the aphid and sap. Field management conditions are poor, and the occurrence of locusts is very serious. In addition, high temperatures above 25°C will reduce the host's resistance to the virus, and it will also facilitate the propagation, migration, or disease transmission of the locust vector, which will facilitate the disease's expansion and increase the severity of the disease. light. Variety disease resistance and cultivation measures will affect the occurrence of this disease.
Prevention and treatment of viral diseases:
Virus disease is one of the major diseases of potato. It can lead to physiological and metabolic disorders of plants, reduced vitality, resulting in a substantial reduction in production. With the development of virus detection technology, it has been found that almost all potato varieties are infected with one or more viruses. The reproduction of the virus is closely linked to the normal metabolic processes of the plant body. Unlike insects, nematodes, fungi, and bacteria, control using chemical agents is ineffective. It is known that some virus inhibitors are also harmful to the plant itself, and at the same time, the inhibitor cannot cure the whole plant, and the virus resumes its previous concentration when the use of the agent is stopped.
The use of chemical agents to kill poisoned insects can reduce the spread of some viruses. However, some viruses are transmitted through contact with the virus or by sucking and sucking (acupuncture). The use of insecticides for the prevention of viral diseases is also ineffective. Practice has shown that, according to locust relocation monitoring, the effect of early seedlings harvesting, harvesting of seed potatoes, and avoidance of aphid transmission of viruses is significant.
The existing method for removing one or several viruses from self-susceptible varieties includes heat treatment and shoot tip culture. The use of potato seed (because no virus can infect seed seed) produces a virus-free seed potato, that is, seed seed - real-potato - seed-retaining biological therapy, which is applied in southwest mountainous regions in China, Inner Mongolia, Heilongjiang and other places. The effect is significant.
(I) Heat treatment and stem tip culture Heat treatment methods have been confirmed in the 50's to passivate the potato leafroll virus. The tuber virus in tubers of some species can be completely removed by heat treatment of tubers at 35°C for 56 days or 36°C for 39 days. In recent years, the use of variable temperature treatment, especially the treatment of buds seed potato.
(b) The selection of disease-resistant and disease-free seed potatoes currently has some varieties that have field resistance to certain viruses. For example, catacladin has field resistance to Y virus and A virus, but there is no resistance to virus disease in the main cultivars in China. At present, virus-free seedlings are usually selected as the virus-free medium after shoot tissue culture, and virus-free seed potatoes propagated stepwise under isolation conditions are used for production. In addition, the control of aphids and the removal of diseased plants are also common methods in production.
(3) Premature control of maggots before and after emergence, especially stripe mosaic virus, which is based on non-persistent transmission of maggots, must be prevented. The use of agents see this article locust control law.
(d) Improve cultivation practices. Including the retention of farmland away from Solanaceae vegetables; early removal of diseased plants; intensive cultivation, high ridge cultivation, timely soil cultivation; to avoid partial application of nitrogen fertilizer, increase phosphorus and potassium fertilizer; pay attention to cultivator weeding; control autumn water, prevent flooding.
(5) In the early stage of disease, spray anti-virus (0.5% mushroom proteoglycan) 300 times or 20% virus A wettable powder 500 times, 5% bacteria water agent 5. 0 times liquid, 1.5% of the disease Ling K emulsion 1000 times, 15% virus will be WP 500 to 700 times.
It can lead to the physiological metabolism of plants, reduced vitality, resulting in a large reduction in production. In severe cases, it can reduce production by 70%--80%, and there is no even production of commodities. At present, there are 18 viruses that can infect potato in the world, including one kind of virus and two kinds of mycoplasma. There are 9 species of viruses that are specifically parasitic on potatoes, and 7 species that are found in the country. The seven viruses are Potato Virus (PVX), Potato Virus 4PVY, Potato Virus (PVS), Potato Virus M (PVM), Potato Violet Mosaic Virus (PVMA), Potato Virus A (PVA), and Ma Xing. Leaf Rolling Virus (PLRV). In addition, some viruses that infect tobacco, cucumber, tomato, etc. also infect potatoes.
Symptoms There are 3 types of common potato virus disease. Chlorophyll of mosaic leaves is unevenly distributed, showing greenish greenish greenish or yellowish greenish mottled mosaics. In severe cases, the leaves are shrunken, the whole plant is dwarfed, sometimes accompanied by veins and leaves transparent; necrotic type leaves, veins,
Petiole, shoots and stems may have brown necrotic spots. The development of lesions is connected to necrotic streak. When severe, the whole leaf is withered or wilting. The leaf-wrapped leaves turn inward along the main vein or from the edge and become hard and leathery. In severe cases, each leaflet is tubular. In addition, there was compound infection that caused potato plaque necrosis.
The pathogenic potato virus X (PVX for short) causes light mosaic disease on potatoes, sometimes with mottled or ring spots. The virions are linear, 480 to 580 nm long, and have a wide host range. Systemic infections are mainly of the Solanaceae family. The virus dilution limit was 100,000 to 1,000,000 times, and the inactivation time of the inactivated domain 68-75°C was more than one year in vitro. The potato virus S (Potato virus S, PVS for short) causes mild shrinking and mosaicism or non-obvious disease in potatoes. The virions are linear, 650 nm long, and their host range is narrow. Plants that are infested by the system are limited to a few plants of the Solanaceae family. The disease sap dilution point is 1-10 times, the passivation temperature is 55-60°C, and the survival time in vitro is 3-4 days. Potato virus A (PVA) causes mild mosaic or non-obvious disease in potatoes. The virions are linear, 730 nm long, and their host range is narrow, infecting only a few plants of the Solanaceae family. Disease sap dilution point 10 times, passivation temperature 44-52 °C, 12-18 hours of survival in vitro. Potato virus Y (PVY) causes severe mosaic or necrotic spots and necrotic streak spots on potatoes. The virions are linear and 730 nm long. The virus has a wide host range.
Can infect a variety of plants in Solanaceae. Disease sap dilution point 100 to 1000 times, passivation temperature 52-62 °C, in vitro survival period of 1-2 days. The potato leafroll virus (Potat oea fro 1 1 1 virus, abbreviated as PLrV) has a virosomal globular shape with a diameter of 25 nm. The host area of ​​the virus is mainly Solanaceae. Roll leaf disease was induced on potato, the virus dilution point was 10000 times, the passivation temperature was 70°C, the survival time was 12-24 hours in vitro, and 4 days survived at a low temperature of 2°C. In addition, TMV can also infect potatoes.
Transmission routes and onset conditions In addition to PVX, the above viruses can be transmitted through the aphid and sap. Field management conditions are poor, and the occurrence of locusts is very serious. In addition, high temperatures above 25°C will reduce the host's resistance to the virus, and it will also facilitate the propagation, migration, or disease transmission of the locust vector, which will facilitate the disease's expansion and increase the severity of the disease. light. Variety disease resistance and cultivation measures will affect the occurrence of this disease.
Prevention and treatment of viral diseases:
Virus disease is one of the major diseases of potato. It can lead to physiological and metabolic disorders of plants, reduced vitality, resulting in a substantial reduction in production. With the development of virus detection technology, it has been found that almost all potato varieties are infected with one or more viruses. The reproduction of the virus is closely linked to the normal metabolic processes of the plant body. Unlike insects, nematodes, fungi, and bacteria, control using chemical agents is ineffective. It is known that some virus inhibitors are also harmful to the plant itself, and at the same time, the inhibitor cannot cure the whole plant, and the virus resumes its previous concentration when the use of the agent is stopped.
The use of chemical agents to kill poisoned insects can reduce the spread of some viruses. However, some viruses are transmitted through contact with the virus or by sucking and sucking (acupuncture). The use of insecticides for the prevention of viral diseases is also ineffective. Practice has shown that, according to locust relocation monitoring, the effect of early seedlings harvesting, harvesting of seed potatoes, and avoidance of aphid transmission of viruses is significant.
The existing method for removing one or several viruses from self-susceptible varieties includes heat treatment and shoot tip culture. The use of potato seed (because no virus can infect seed seed) produces a virus-free seed potato, that is, seed seed - real-potato - seed-retaining biological therapy, which is applied in southwest mountainous regions in China, Inner Mongolia, Heilongjiang and other places. The effect is significant.
(I) Heat treatment and stem tip culture Heat treatment methods have been confirmed in the 50's to passivate the potato leafroll virus. The tuber virus in tubers of some species can be completely removed by heat treatment of tubers at 35°C for 56 days or 36°C for 39 days. In recent years, the use of variable temperature treatment, especially the treatment of buds seed potato.
(b) The selection of disease-resistant and disease-free seed potatoes currently has some varieties that have field resistance to certain viruses. For example, catacladin has field resistance to Y virus and A virus, but there is no resistance to virus disease in the main cultivars in China. At present, virus-free seedlings are usually selected as the virus-free medium after shoot tissue culture, and virus-free seed potatoes propagated stepwise under isolation conditions are used for production. In addition, the control of aphids and the removal of diseased plants are also common methods in production.
(3) Premature control of maggots before and after emergence, especially stripe mosaic virus, which is based on non-persistent transmission of maggots, must be prevented. The use of agents see this article locust control law.
(d) Improve cultivation practices. Including the retention of farmland away from Solanaceae vegetables; early removal of diseased plants; intensive cultivation, high ridge cultivation, timely soil cultivation; to avoid partial application of nitrogen fertilizer, increase phosphorus and potassium fertilizer; pay attention to cultivator weeding; control autumn water, prevent flooding.
(5) In the early stage of disease, spray anti-virus (0.5% mushroom proteoglycan) 300 times or 20% virus A wettable powder 500 times, 5% bacteria water agent 5. 0 times liquid, 1.5% of the disease Ling K emulsion 1000 times, 15% virus will be WP 500 to 700 times.
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